^^ most petrol engine Mitsus will be M20x1.5mm thread, but the diesels often use a much larger diameter thread. The Mitsu thread and gasket diameter is shared with many Hondas, most Subarus, many Mazdas etc. There are a ton of different filters you can use on the GVR-4. I personally use Mitsu OEM filters on mine - I am using the smaller diameter but longer length filter from later model Mitsus rather than the chode filters they originally would have used.